While we should not overestimate this, the story is highly plausible given the extremist ideas of Zarqawi which are far more takfiri-Kharijite oriented than even the ideology of the main branch of al Qaida run by bin Laden and al-Zawahiri. The predominance of Saudis and Saudi money in al Qaida Iraq squares with the earlier analysis by the Jamestown Foundation and a more recent one.

A point which indicates that the Saudi security services are either tasked beyond their means by the magnitude of pro-Jihadi sentiment in the population that their own Wahhabi-Salafist ideology has stoked or very little effort is going to stem the flow of volunteers and cash northward (most likely because, as with the previous exodus to Afghanistan, Saudi authorities are happy to see the troublemakers go. Some won't be coming back).

Kharijite, while the ancient ones can be spun to sound a lot like the modern Hijra wa Takfir groups, are not really of the same cloth.

The wiki article strikes me as being ... not unbalanced but sensationalist. I would not call the Takfiris "kharijites" as modern Kharijites are not in any way takfiri as a general matter, and insofar as it fits, it fits a slightly analogous situation over a thousand years past.

In short, it's not a good tag to use as it confuses and is a bit of an anachronism.